Treatment of metals with acid liquors



252; COMPOSITIONS,

Patented Oct. 14, 1930 UNITED STATES Exami PATENT OFFICE MAX HARTMANN, OF RIEHEN, NEAR BASEL, AND WILLI KLARER, OF BASEL, SWITZER- LAND, ASSIGNORS TO THE FIRM SOCIETY OF CHEMICAL INDUSTRY IN BASLE, OF

BASEL, SWITZERLAND TREATMENT OF METALS WITH ACID LIQUORS 1T0 Drawing. Application filed June 4, 1929, Serial No. 368,426, and in Switzerland June 7, 1928.

The present invention relates to an improvement in the art of pickling iron, especially malleable iron, steel, iron alloys and articles therefrom, as wires, wire ropes, sheets, etc. It comprises the new pickling liquors, the process of making same, the application thereof, as well as the metal treated with the new pickling liquors.

This invention is based on the observation that quite generally the products soluble in dilute mineral acids which are obtained by condensing aldehydes keiongsand suitable acid 'clil'orides such. as phosgene, w itlijalromaticjamiiid-comnounds glijromati q nitrocompounds and subsequent reduction arefiemarkably suitable additions to acid liquids for treating metals. They are particularly suitable as additions to pickling baths, liquid soldering fluxes or the like, which serve for removing from metals impurities, such as rust, scale or the like.

' These products comprise quite generally compounds containing at least two aryl nuceli which themselves contain an NH -group or a substituted NH -group and which are bound by a so-called central carbon atom. This central carbon atom itself may be bound with hydrogen, oxygen, alkyl or aryl residues.

Among these products or classes of products there may be mentioned diaminodi;

phenyln ethane, diaminoditollvqlmethane, di;

aminodinaplithylnieflfifiieoft e corresponding symmetrical and unsymmetrical primary or secondary N-substitution products, for example fl kfistatharnethyldiaminodiphenylmethane ;,further the corresponding products which may be obtained with acetaldehyde or acetone instead of with formaldehyde; as well as ketones, such as 4:4L-tet ramethyldiaminobenzophenone, also the triaifiifiotriphenylmethane or, quite generalTi,theleii'cocompounds of the triarylmethane dyestuifs containing amino-groups, such as l eucocr stalliolet or leuco malachite green, or'tlie corresponding quaternary ammonium bases of all these. compounds. Particularly suitable are'the products the salts of which correspond to the general formula wherein R R R R R R ==hydrogen, alkyl, aralkyl or aryl, R,=hydrogen or alkyl, and R =hydrogen, alkyl or aryl, and wherein' a; and 3 means the same or different an- 1011s.

It has been found most unexpectedly that these compounds, when added even in very small proportions to acid liquid, prevent more or less completely the attack of metals by these liquids without, however, affecting the solvent action of the liquids for rust, oxide or the like. The advantages of such an addition are clear; there is saving of metal and acid, diminution of the formation of hydrogen and acid vapors accompanied by diminished brittleness due to the pickling, andincreased protection for the worker who has to carry out the operation of pickling.

The above mentioned compounds may be used not only alone or in mixture with each.

other also in combination with various substances, such as mineral salts, sulfite cel: lulose liquor, sulfonatedoils, mono. and unsymmetricalm,diracylatei diamines and the corresponding ammoniuggfifisgtail produ c t sor the like.

The following examples illustrate the invention, the parts being by weight Example 1 1000 parts of hydrochloric acid of 15 per cent. strength are mixed with 0.2 part of the hydrochloride of 4:4-tetramethyldiaminodiphenylmethane or with 0.1 part of the hydrochloride of 4:4'- or 2:2'-tetramethyldiaminodinaphthylmethane. The solution may c will i 1,778,634 p i I ent for treating 3. Pickling baths containing compounds used at once as an ag 'ietals. soluble in dilute mineral acids and corre- Example 2 sponding with the general formula ,1000 parts of hydrochloric acid of per R N ary1H/C\Hary1 N 7o ent. strength arefmixed with 0.1 part of t(l11e .ydrochlo-ride 0 3:3 diamino 4 4' iziethyldiphenylmethane. The product may f i 5. R3 i B4 hydrfigen or such 1e used immediately as an agent for treating a {y S w lch contam not more t an two netals. bon

;. 4. Pickling baths containing compounds Example 3 soluble in dilute mineral acids and corre- 1000 parts of hydrochloric acid of 15 per Spondmg Wlth the general formula tent. strength are mixed with 0.1 part of the R1 hydrochloride of 4 4-tetramethyldiaminon R4 diphenylmethaneand 0.9 part of sulfite cellurein R R R and B =hydrogen or such Hose liquor. The solution can be used at once whe alkyls which contain not more than two carjas a metal treating agent.

Y Ema/m Z6 4 bon atoms, and wherein .aryl standsfor a p benzene or naphthalene nucleus.

Sheet iron is immersed until it has been 5. Pickling baths containing compounds completely pickled in a pickling liquor consoluble in dilute mineral acids and correjtaining per 1000 parts of hydrochloric acid sponding with the formula of 15 per cent. strength 0.2 part of the hy- 0,135

f'drochloride of 4:4J-tetramethyldiaminodi- CH H5 i phenylmethane or with 0.1 part of the hy- 2 5 a thyldil drochloride ofA 4'- or 2:2:1- tetrami aminodinaphthy methane. he pic 'lmg is I n witness whereof we have hereunto L finished in a shoit time without dissolution Signed our names this Qith y of y 1929. I

of noticeable quantities of the metal. The V sheets are then removed and are ready for further treatment (ti ning, zincing, varnishing, soldering or the like). If for any reason the iron is not immediately removed rom the pickling liquor there is no appreciable 1c; further action of the acid and in consequence f practically no dissolution of the metal, such as is known to occur in a pickling bath of the ordinary kind.

The same results are obtained with the corresponding tetraethyl-compounds. In like manner a pickling bath consisting of sulfuric acid or mixtures of acids may e treated; instead of the compounds mentioned 45 in the examples other compounds as disclosed in the introduction hereto may be used. The operation may be conducted cold or hot.

What we claim is I 1. Pickling baths containing compounds I soluble in dilute mineral acids and corre- 1w sponding with the general formula wherein R R R R =hydrogen, alkyl, 121- aralkyl or aryl, R =hydrogen or alkyl, and B =hydrogen, alkyl or ar alkyl.

2. Pickling baths containing compounds soluble in dilute mineral acids and corresponding with the general formula I P B1 I R:

N 1-0 1-N/ 3 any my m Bu 6 wherein R R B R ,B ,R =hydrogen or alkyl. I 1:3 

